In terms of incomprehensible enormity, what is commonly known as the “Spanish Flu” is in a league of its own. It is commonly estimated to have killed between 50 and 100 million people. If it were a genocidal dictator it would outrank all its peers by an order of magnitude. Compared with the World Wars, it .
In doing research on Indian census coding schemes for one of my projects, I just stumbled across this table that helps put the Great Influenza into perspective. Wikipedia cites a mortality rate of 5% in India from the 1918 pandemic. In that table, you can see that (ignoring other factors) it appears to have totally undone an entire decade of population growth in that country. Stunning.
Incidentally The Great Influenza is among my favorite books, a wonderful mix of medical history, scientific thriller, and horror novel. Read it if you want to freak out about the next flu strain that Adam brings up on this blog.